In the case of a currently commercially available vacuum insulator, the vacuum insulator comprises a core material and an outer cover material, wherein the core material comprises an inorganic compound, such as glass wool, fumed silica and aerogels, and the outer cover material comprises a sealing layer, such as nylon/PET/aluminum foil, or in addition to an aluminum deposition layer, polyethylene (PE), polypropylene (PP), and the like. Further, a getter material is employed to ensure long-term durability of the vacuum insulator, and comprises a humectant, such as calcium oxide (CaO), zeolite and silica gel, and a metal powder.
In particular, the outer cover material for the vacuum insulator is exposed to external impacts and external environmental changes, i.e., in external temperature and humidity, which influences the effects and performances of the vacuum insulator, and, therefore, continued researches are being conducted for the outer cover material for the vacuum insulator.